Hydration Pack vs. Bottles
Interesting. Scott Jurek just tweeted about a study evaluating the energy drain of hand-held bottles versus a hydration pack. Here's some other info from one of the participants. There's no paper yet, the researcher is presenting a poster in June. In summary, packs are supposed to be better, but the sample size might be 5. [Actually, I don't see anywhere that directly indicates the sample size other than the first commenter on the blog. But if it is in fact only 5, well, I'd believe this study, but only if one of those five people were me.]